Lewis, I and P Blood Group Systems
This chapter gives a review of the Lewis, I and P blood group systems. The antigens in the Lewis blood group systems are composed of terminal carbohydrate moieties added to protein or lipid backbones in a configuration similar to that of the ABO antigens. The Lewis blood group antigens Lea and Leb are synthesized by two independent fucosyltransferases and the corresponding antibodies are usually not of clinical significance. The Lewis antigens are not intrinsic to the red blood cell membrane but are synthesized by intestinal epithelial cells, circulate in the plasma either free or bound to lipoproteins and are then passively absorbed onto the RBC membrane. Antibodies to the Lewis antigens are primarily IgM, naturally occurring and not usually clinically significant except in rare case of hemolytic transfusion reactions. The P and GLOB blood group systems are discussed and the P antigens are usually defined by sugars added to precursor glycoshingolipids and their synthesis occurs by sequential addition of monosaccharides to the precursor molecule by glycosyltransferases. © 2009 Elsevier Inc. All rights reserved.
